[dm-devel] [PATCH v2 19/26] bounce: Refactor __blk_queue_bounce to not use bi_io_vec
Tejun Heo
tj at kernel.org
Fri Sep 21 00:25:55 UTC 2012
Hello, Kent.
On Mon, Sep 10, 2012 at 05:22:30PM -0700, Kent Overstreet wrote:
> A bunch of what __blk_queue_bounce() was doing was problematic for the
> immutable bvec work; this cleans that up and the code is quite a bit
> smaller, too.
>
> The __bio_for_each_segment() in copy_to_high_bio_irq() was changed
> because that one's looping over the original bio, not the bounce bio -
> since the bounce code doesn't own that bio the __ version wasn't
> correct.
I do like the new implementation. I think the function is broken
before and after tho. Allocating from fs_bio_set from block layer is
never safe and nothing seems to prevent multiple allocators compete in
the bounce page mempool. This will need a separate bioset and the
multiple mempool allocation would have to be put inside a mutex.
Also, how was this tested?
Thanks.
--
tejun
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